It can be difficult to screen semiconductor devices for functionality. Defects observed at the package interface may cause the entire device to fail. Previous approaches to determining whether a device is functional include wafer sort and final packaged testing. However, because the test equipment associated with such tests is often expensive, sophisticated capital equipment, the tests themselves become expensive, with the cost of the test increasing with test duration.
Further, even after devices have been packaged, tested and shipped, they are not all perfect, and failures do occur in the field, by which we mean locations remote from the manufacturer of the devices. For example, a “field location” may refer to the facilities of a customer, distributor, or an end user. A field location may be a sales office of the IC manufacturer. Conventionally, suspect or failed devices have to be shipped from a field location back to the manufacturer in order to evaluate them, often incurring the expenses and delays that are typically associated with international shipments.